The invention relates generally to an apparatus for treating particulate material.
DE 199 04 147 A1 discloses an apparatus for treating particulate material, which comprises a process chamber for holding and for treating the material. A circular cross section bottom of the process chamber comprises mutually overlapping, approximately flat guide plates, between which slots are formed, via which process air can be introduced into the process chamber with a substantially horizontal movement component. In this case, the slots are arranged in such a way that two opposed flows of introduced process air oriented toward each other and running substantially horizontally are produced, impinge on each other along a breaking-up zone and are deflected into a flow oriented substantially vertically upward.
An apparatus of this type is used to dry, to granulate or to coat particulate material.
A gaseous medium, process air, as it is known, is introduced into the process chamber via the bottom, thereby passing through the numerous slots between the mutually overlapping guide plates and entering the process chamber oriented approximately horizontally. In the breaking-up zone, the flows oriented toward each other impinge on each other, are deflected upward, and the process air emerges at the upper end via an exhaust chamber. Because of the force of gravity, the material falls back onto the bottom again, so that a swirling flow circulating approximately circularly develops on either side of the breaking-up zone.
The apparatus mentioned at the beginning has an approximately circular closed bottom, and the process chamber has a cylindrical shape.
Apparatus with a tunnel-like process chamber is also known, what is known as a coating or drying tunnel, in which the material to be treated is not only swirled but is also conveyed gradually from an inlet along the longitudinal direction of the tunnel as far as an outlet. This opens up the possibility of continuous operation.
A fundamental problem in apparatus with tunnel-like elongated process chambers is to transport the swirled material gradually from the inlet to the outlet.
For this purpose, it has become known to arrange the entire apparatus at an angle, so that this transport takes place with the aid of the force of gravity.
Furthermore, it has become known to move the apparatus additionally in the direction of inclination by means of eccentrics or vibrators, in order to assist the movement of the material.
In practical use, it has been established that this is very expensive in terms of apparatus, in particular in the case of large and heavy apparatus. Furthermore, it has been established that the swirled material tends to layer or accumulate during its movement from the inlet to the outlet, that is to say the layer thickness of the swirled material increases toward the outlet.
This is disadvantageous inasmuch as, because of these relatively uncontrollable conditions, non-uniform treatment results are achieved. If the treatment of a particle in the form of a capsule is taken as an example, such as is often found in the pharmaceutical sector, then this capsule arises during the production process as a hollow body, whose interior is filled with the galenic preparation of the medicament, generally in the form of a liquid. The wall of the capsule immediately after the production process is a gel-like, still soft body, which normally has high moisture content. During drying, the intention is for this capsule wall to be dried out by the removal of moisture and, as a result, hardened and solidified. This process is intended to proceed in a controlled manner, that is to say not too quickly and not too slowly; the gel layer dried out gradually is not intended to embrittle and form any cracks, since otherwise there is the danger that the outer layer becomes leaky or separates. Furthermore, the intention is to ensure that the liquid content remains in the interior and does not emerge via the outer layer of the capsule as a result of the drying process.
Thus, as it passes through the elongated tunnel-like process chamber, the capsule layer changes from an initially rather soft, viscous, possibly tacky consistency to a harder, low-moisture, thoroughly dried, solid consistency. The stratification character of the material compound rolled around in the process chamber therefore changes from the inlet to the outlet.
Furthermore, apparatus of this type is intended to permit flexible throughputs, so that, for example, it can be arranged between an apparatus for producing the capsule and a subsequent packaging apparatus, for example blister packing.
It is therefore an object of the present invention to provide an apparatus for treating particulate material comprising an elongated, tunnel-like process chamber which permits a good treatment result with a continuous throughput under reproducible, easily controllable and therefore manageable conditions.